SPot North 2018 Results

Nitrogen at SPot Farms

Mark Stalham & Marc Allison

Hypothesis: does N application drive yield?

0

20

40

60

80

100

0 50 100 150 200 250 300 350 400

Yiel

d (

40

-90

mm

@ 2

3.3

% D

M, t

/ha)

Nitrogen applied to crop (kg N/ha)

Data from 556 processing crops 2010-2016

Mean ware yield at 23.3 % DM = 50.0 t/ha

Mean N application rate = 201 kg N/ha

Survey data suggest otherwise

British Survey of Fertilizer Practice & AHDB

0

50

100

150

200

250

0

10

20

30

40

50

60

1970 1980 1990 2000 2010 2020

Ave

rage

N a

pp

licat

ion

(kg

N/h

a)

Mai

ncr

op

yie

ld (

t/h

a)

Maincrop yield

Average N application

Summary of SPot N trials (2016-2018)

SPot site Year Variety N treatments

Summary of N

effects on yield

Yields >40

mm (t/ha) Tuber DM (%)

East 2016 R Burbank Split N, All N in

seedbed (both 260)

No effect 68.2, 68.3 22.0, 22.1

2017 Brooke Split N, All N in

seedbed, Placed N

(all 220), 160, 180,

220, 160+30

No effect of rate

or timing. Placed

lower

61.0, 61.1,

55.7, 61.2,

59.2, 61.0,

62.3

24.5, 24.8, 25.0,

24.3, 24.3, 24.7,

24.3

2018 Estima 180, 210, 240, 270 No effect 54.8, 56.9,

56.6, 55.1

18.9, 18.8, 18.4,

18.5

North 2018 M Piper 120, 150, 180,

150+30

No effect 49.7, 48.1,

49.3, 50.7

23.6, 23.4, 23.2,

23.4

South West 2017 Electra 90, 120, 150 No effect 58.7, 61.7,

61.3

17.1, 16.3, 16.4

2018 Electra 0, 30, 60, 90, 120 No effect 72.0, 61.2,

72.4, 73.4,

72.3

16.4, 15.7, 15.6,

15.8, 15.4

Scotland 2017 M Piper 177, 147, Liquid,

Injection

Injection lower 54.3, 51.2,

54.5, 49.8

19.2, 19.4, 18.5,

18.4

2018 M Piper 176, 147, 120,

Placed

TBA TBA TBA

Setting the N rates for SPot North 2018

Step Process Factors Outcome

1 Calculate soil nitrogen

supply (SNS)

Cereal stubble, shallow,

sandy loam soil in a low

rainfall area

SNS Index = 1

(soil will supply 60-80 kg

N/ha)

2 Identify determinacy

group

Maris Piper Variety group = 3

(indeterminate, long

haulm longevity)

3 Calculate season length 24 May (emergence) to

end August (defoliation)

Season length = 100

days

4 Calculate initial N

requirement of crop

133 kg N/ha

5 Calculate supply from

organic manures

Nothing applied to previous

crop

But soil OM is 2.7 %

6 Fertilizer required 130 kg N/ha

Spot N 2018 Hypotheses

1. The optimum N for Maris Piper on the site would be < 150 kg/ha not the

commercial rate of 180 kg/ha

2. Top-dressing does not increase yield compared with all N in seedbed

3. Reducing N increases the risk of black dot infection

4. Reducing N increases the risk of bruising

Can we use soil tests to guide N fertilizer recommendations?

0

100

200

300

400

500

0 100 200 300

Op

tim

um

N a

pp

licat

ion

rat

e (k

g N

/ha)

Soil mineral N measured in the spring (kg N/ha)

Neeteson (1990, 0-60 cm)

Johnson & Chambers (1998, 0-60 cm)

Neeteson (1984, 0-30 cm)

Allison (2003, 0-90 cm)

Relationship between tuber N uptake and tuber dry matter yield

y = 15.25 (± 0.075)xR² = 64.2P < 0.001

0

50

100

150

200

250

300

350

400

450

500

0 5 10 15 20 25

Tub

er N

up

take

(kg

N/h

a)

Tuber DM yield (t/ha)

Big N uptake = big yield?

y = 0.0882x + 30.208R² = 0.2628

0

20

40

60

80

0 100 200 300 400 500Maximum recorded total N uptake (kg N/ha)

Yiel

d (

40

-90

mm

@ 2

3.3

% D

M, t

/ha)

Data from 402 processing crops 2010-2016 where N uptake was measured

Mean ware yield at 23.3 % DM = 49.6 t/ha

Mean total N uptake = 220 kg N/ha

Effect of N on yield formationRusset Burbank, CUF 2008

Nitrogen

applied

(kg N/ha)

Total

N uptake

(kg N/ha)

Integrated

GC

(% days)

Radiation

absorbed

(TJ/ha)

Total

DM

(t/ha)

Harvest

index

(%)

Total FW

yield

(t/ha)

0 142 7843 12.8 14.2 93 56.7

125 197 8622 13.8 16.6 87 64.7

250 225 9071 14.2 17.5 87 69.1

375 308 10262 15.3 18.9 87 77.8

S.E. 25.1 318.2 0.38 1.28 2.5 3.78

Harvested 29 September

Relationship between N uptake by tubers and fertilizer N application

0

50

100

150

200

250

300

350

400

450

500

0 50 100 150 200 250 300 350

Tub

er N

up

take

(kg

N/h

a)

Nitrogen applied (kg N/ha)

y = 108.4 (± 8.38) + 0.317 (± 0.041)xR² = 4.0P < 0.001

What factors affect the amount of N taken up by the crop?

?

N application N uptake Tuber Yield 4 %

96 %

PCN

Water

(deficient/excess)

Soil compaction

Environment

(radiation/temperature)

Pathology

?

Soil Nitrogen Supply

Effect of compaction and irrigation on nitrogen uptake. Maris Piper CUF 2006

0

1

2

3

4

5

6

7

8

1-May 1-Jun 2-Jul 2-Aug 2-Sep 3-Oct

Tota

l N u

pta

ke (

kg N

/ha/

day

)

Compacted-Irrigated

Compacted-Rainfed

Uncompacted-Irrigated

Uncompacted-Rainfed

Approx. time of T.I.

What do we mean by N use efficiency?

0

80

160

240

320

0 80 160 240 320

Nit

roge

n r

emo

ved

in t

ub

ers

(kg

N/h

a)

Nitrogen applied as fertilizer (kg N/ha)

Fertilizer

N applied

(kg N/ha)

N in

tubers

(kg N/ha)

Increase

in N

uptake

(kg N/ha)

Efficiency

of N use

(%)

0 94 - -

80 164 70 88

160 212 48 60

240 239 26 33

320 243 4 5

Fertilizer N

not in

tubers

(kg N/ha)

-

10

32

54

76

Effect of irrigation, N application and variety on tuber yield. CUF Reference Crop 2006-2017

Estima Cara

Rain-fed Irrigated Rain-fed Irrigated

kg

N/hat/ha

kg

N/hat/ha

kg

N/hat/ha

kg

N/hat/ha

Mean146

± 27.6

43.6

± 4.77

193

± 19.5

65.4

± 3.42

87

± 21.8

58.0

± 3.53

87

± 22.5

70.1

± 4.74

Irrigation increased optimum N application rate by 47 kg N/ha in Estima and

0 kg N/ha in Cara

Data from Firman

SPot Farm East 2016Split N vs Seedbed N comparison

0

20

40

60

80

100

23-May13-Jun 04-Jul 25-Jul 15-Aug05-Sep

Gro

un

d c

ove

r (%

)

Split N

Seedbed N

20

25

30

35

40

24-Jun 08-Jul 22-Jul 05-Aug 19-Aug

SPA

D m

ete

r re

adin

g

160

180

220

160+Topup

SPAD Meter: measuring leaf chlorophyll content for predictions of N deficiency

20

25

30

35

40

24-Jun 08-Jul 22-Jul 05-Aug 19-Aug

SPA

D m

ete

r re

adin

g

Standard

Over-water

Are we leaching much N?Soil NO3 sensors (Tony Miller, JIC + Agrii)

SPot North N Experiment yield

N

treatment

No.

plants

(000/ha)

No.

stems

(000/ha)

Total

no.

tubers

(000/ha)

Total

yield

(t/ha)

Yield

>45 mm

(t/ha)

Tuber

DM

conc.

(%)

Tuber

DM

yield

(t/ha)

120 30.6 107 408 49.7 43.1 23.6 11.7

150 29.2 94 345 48.1 43.5 23.4 11.3

180 30.6 123 383 49.3 45.3 23.2 11.4

150+30 30.6 106 400 50.7 46.5 23.4 11.9

S.E.

(12 D.F.)

2.11 11.8 34.4 1.74 1.56 0.27 0.47

SPot North N Black Dot

N treatment

Incidence

(%)

Incidence

(angular

transformation)

Proportion

<5 % SA

(%)

Severity

(% SA)

120 53.6 47.1 92.6 2.13

150 36.6 36.9 91.6 1.32

180 51.6 46.2 87.2 2.41

150+30 53.8 47.2 79.4 3.38

S.E.

(12 D.F.)

6.99 4.16 4.90 0.954

SPot East Black dotMain effects of N

Nitrogen

Incidence

(%)

Proportion

<5 % SA

(%)

Severity

(% SA)

180 56.4 74.8 4.97

210 55.4 74.8 6.12

240 50.2 77.0 5.65

270 57.5 73.9 5.60

S.E. (30 D.F.) 3.60 2.83 0.783

No effect of N rate or timing on black dot

SPot Scotland Black dotEffects of N

Nitrogen

Incidence

(%)

Proportion

<5 % SA

(%)

Severity

(% SA)

N1 Standard 147 kg,

top-dress 32 kg

48

(±8.4)

82

(±9.1)

3.7

(±2.09)

N2 Standard 147 kg, no

top dress

52

(±18.8)

81

(±10.8)

3.4

(±2.09)

N3 Reduced 90 kg, no

top-dress

50

(±10.0)

82

(±3.2)

3.9

(±1.28)

N4 Placed 147 kg, top-

dress 32 kg

43

(±16.5)

85

(±10.4)

2.7

(±2.20)

No effect of N rate, timing or position on black dot

Increased N delays skinset?

0

2

4

6

8

10

12

120 N 150 N 180 N 150+30 N

SPot N 2018 Maris Piper

Skinning (% surface area)

0

2

4

6

8

10

12

180 N 210 N 240 N 270 N

SPot E 2018 Estima

Skinning (% surface area)

No evidence that reduced N increases bruising

0

20

40

60

80

180 N 210 N 240 N 270 N

SPot E 2018 Estima

Incidence (%) Bruise depth (mm)

0

20

40

60

80

120 N 150 N 180 N 150+30 N

SPot N 2018 Maris Piper

Incidence (%) Bruise depth (mm)

Isn’t it about what is sold rather than yield digs?SPot Scotland 2017 Packout (Albert Bartlett)

Trial 1 2 3 4

Treatment Planting

Top dress

Liquid

Standard

(177 N)

Standard

Ridge

inject

(175 N)

Standard

No top

dress

(147 N)

Standard

Standard

(176 N)

Crop

harvested

No. boxes 23 24 24 22

Graded

product

Tonnes 14.24 14.70 15.88 14.12

Packout % 64.6 62.9 67.6 64.9

Yield packed t/ha 37.5 37.8 40.9 36.1

Summary of SPot N trials (2016-2018)

SPot site Year Variety N treatments

Summary of N

effects on yield

Yields >40

mm (t/ha) Tuber DM (%)

East 2016 R Burbank Split N, All N in

seedbed (both 260)

No effect 68.2, 68.3 22.0, 22.1

2017 Brooke Split N, All N in

seedbed, Placed N

(all 220), 160, 180,

220, 160+30

No effect of rate

or timing. Placed

lower

61.0, 61.1,

55.7, 61.2,

59.2, 61.0,

62.3

24.5, 24.8, 25.0,

24.3, 24.3, 24.7,

24.3

2018 Estima 180, 210, 240, 270 No effect 54.8, 56.9,

56.6, 55.1

18.9, 18.8, 18.4,

18.5

North 2018 M Piper 120, 150, 180,

150+30

No effect 49.7, 48.1,

49.3, 50.7

23.6, 23.4, 23.2,

23.4

South West 2017 Electra 90, 120, 150 No effect 58.7, 61.7,

61.3

17.1, 16.3, 16.4

2018 Electra 0, 30, 60, 90, 120 No effect 72.0, 61.2,

72.4, 73.4,

72.3

16.4, 15.7, 15.6,

15.8, 15.4

Scotland 2017 M Piper 177, 147, Liquid,

Injection

Injection lower 54.3, 51.2,

54.5, 49.8

19.2, 19.4, 18.5,

18.4

2018 M Piper 176, 147, 120,

Placed

TBA TBA TBA

Financial summary of SPot N trials to date

Commercial split N All N in seedbed Financial Placed/injected Financial

61.2 t/ha +0.1 t/ha +£20/ha -4.9 t/ha -£980/ha

Commercial rate Optimal rate N saving Financial

57.2 t/ha +0.8 t/ha -53 kg/ha +£197/ha

Summary

• Used RB209 to calculate N requirement for crop and site and mostly found

30-60 kg N/ha lower than commercial rate being used on surrounding crop

• Experiments and strip trials showed no evidence of loss of yield from these

lower rates

• Placed or injected N tended to produce lower yields than broadcast

• No evidence that much N leached out of the rooting profile during the growth

period on heavily irrigated sandy soils, but canopies were paler and shorter-

lived where over-watering took place

• Decreased N did not result in increased bruising

• Decreased N resulted in better skinset

SPot North 2018 P, K, S Results

Site background

• Barn Field, Somerby Top Farm, Lincolnshire (53.5529° N, 0.3726° W)

• Sandy loam texture (78% S, 12% Z, 10% C) with high limestone content

• No PCN found in the trial area in November 2016

• Soil OM of 3.4 % (consequence of pig slurry from the site’s pig unit?)

• pH 8.2

• P Index was 3- (30-31 mg/l)

• K Index 2+ (215-234 mg/l)

• Mg Index 2 (58-60 mg/l)

• SO4 concentration very high (19.5 mg/l)

Site background

• Ploughed, ridged, destoned early May

• Planted 5 May

• Varieties

• Maris Piper (N & S Experiments)

• Royal (P & K Experiments)

• Emergence

• Maris Piper 5 June

• Royal 2 June

• Irrigation ??? mm

Any visible treatment effects on 1 August?

K Background

1. Allison et al. (2001a) found that:

a) Generally, K Index was a poor predictor of the probability of a yield response

b) No more than 210 kg K2O/ha be applied, even on soils with Index 1 or less

c) When applied at the optimal rate for yield, the effects of K fertilizer on tuber DM

concentration were non-significant

d) Exceeding the optimal K application rate caused occasional reductions in tuber DM

concentration, particularly if potassium chloride (KCl) was used

K Hypotheses

1. AHDB RB209 recommended K rate for site was 300 kg K2O/ha to balance

offtake by 50 t/ha crop

2. Different K products have different effects on tuber dry matter

3. Increased K reduces tuber DM

K Treatments• K products:

• None

• Muriate of potash (KCl)

• Sulphate of potash (K2SO4)

• ICL PotashpluS

• K rates:

• 0 kg K2O/ha

• 100 kg K2O/ha

• 200 kg K2O/ha

• 300 kg K2O/ha

• 3 replicate blocks

Yields (main effects of K source and K rate)

K source / rate

Yield

>40 mm

(t/ha)

Total

yield

(t/ha)

Tuber

DM

(%)

DM

yield

(t/ha)

KCl 35.1 37.2 24.9 9.3

K2SO434.5 37.0 25.1 9.3

PotashpluS 35.3 38.2 25.0 9.5

S.E. (22 D.F.) 1.46 1.39 0.15 0.37

0 34.6 36.8 25.2 9.3

100 35.2 38.0 25.1 9.6

200 35.6 37.9 24.7 9.4

300 34.4 37.1 25.0 9.3

S.E. (22 D.F.) 1.69 1.60 0.17 0.43

No effect of K source or rate on yield, and no directional effect on DM%

Fry colour (main effects of K source and K rate)

K source / rate

Fry colour

(0 = USDA 0,

1= USDA 1)

KCl 0.029

K2SO40.038

PotashpluS 0.025

S.E. (22 D.F.) 0.0100

0 0.028

100 0.028

200 0.033

300 0.033

S.E. (22 D.F.) 0.0116

No effect of K source or rate on fry colour

P Background

1. Allison et al. (2001b) found that:

a) Increases in the number of tubers in response to application of P fertilizer only

occurred in soils with P Index 2 or lower and appeared to be associated with an

increase in ground cover by the time of tuber initiation

b) Applications of foliar P had no effect on number of tubers (or yield) and the authors

discouraged this practice

P Hypothesis

1. Foliar P can increase the number of tubers, even on high P Index soils

P Treatments

• No foliar P applied

• 10 l/ha MAGPHOS K applied as foliar spray in 200 l/ha 2 days prior to tuber

initiation (15 June)

• 10 l/ha MAGPHOS K applied as foliar spray in 200 l/ha 2 days prior to tuber

initiation (15 June) and second 10 l/ha 10 days after tuber initiation (27 June)

• 6 replicate blocks

Numbers of tubers

No effect of foliar P on number of tubers

0

100

200

300

400

Control TI-2 only TI-2+TI+10

No

. of

tub

ers

(0

00

/ha

)

10-20 mm 20-30 mm 30-40 mm 40-50 mm

50-60 mm 60-70 mm 70-80 mm 80-90 mm

Tuber yield

P treatment

Yield

>40 mm

(t/ha)

Total

yield

(t/ha)

Tuber

DM

(%)

DM

yield

(t/ha)

No foliar P 45.7 47.6 25.1 11.9

Foliar P at TI 45.1 46.8 24.8 11.6

Foliar P at TI and TI+10 days 44.3 46.3 25.0 11.6

S.E. (10 D.F.) 1.33 1.25 0.49 0.36

No effect of foliar P on yield

S Background

1. Previously, the supply of natural sources of S from the soil was regarded as

sufficient for the potato crop

2. Significantly reduced S deposits from the atmosphere (due to a marked decline

in industrial pollution), and continued use of fertiliser with low S content, S

deficiency has gained increasing attention in many regions causing crops to

become vulnerable to yield reductions

3. Spot North experiment is one of a series being conducted as part of a 3-year

AHDB-funded project on S undertaken by NIAB CUF

S Hypotheses

1. Potato crops are responsive to S fertilizer

2. Product type influences S delivery

3. S can help control common scab

S Treatments

• No S

• 50 kg S/ha (125 kg SO3) applied as ammonium sulphate at planting

• 50 kg S/ha applied as ICL Polysulphate at planting

• 50 kg S/ha applied as liquid sulphur at planting

• 6 replicate blocks

Petiole concentration of SO4 (mg/l)

S treatment mg/l

None 164

Ammonium sulphate† 173

ICL Polysulphate† 167

Liquid S† 177

S.E. (15 D.F.) 8.8

No effect of S application on plant uptake?

†125 kg SO3/ha)

Numbers of tubers and yields

S treatment

Total no.

tubers

(000/ha)

Total

yield

(t/ha)

Tuber

DM

(%)

None 324 44.0 24.2

Ammonium sulphate† 340 42.3 24.1

ICL Polysulphate† 296 41.8 24.0

Liquid S† 396 48.1 24.2

S.E. (14 D.F.) 40.5 3.06 0.22

No effect of S on yield

†125 kg SO3/ha)

Common scab and skin finish defects

S treatment

Common scab

(0=absent, 1=low, 2-

medium, 3=high)

Proportion of tubers

with skin finish

defect (%)

None 1.67 68

Ammonium sulphate† 1.17 75

ICL Polysulphate† 1.67 83

Liquid S† 2.00 87

S.E. (15 D.F.) 0.214 9.6

No effect of S on skin quality?

†125 kg SO3/ha)

Summary of AHDB S Project 2016-2018 (8 sites)

Petiole S04 (mg S/l) Yield (t/ha) Tuber DM %

No S 117 62.7 22.0

With S 134 63.0 22.1

S.E. 5.4 1.50 0.09

Variety Petiole S04 (mg S/l)

Innovator 123-160

VR808 68

Maris Piper 138-170

Royal 98

Russet Burbank 192

Summary

• Don’t do nutrition experiments on high Index soils!

• K Index 2+

• No effect of K source or rate on yield, DM or fry quality

• P Index 3-

• No effect of foliar P on number of tubers

• S soil concentration very high

• No effect on yield or skin quality

• Optimal fertilizer for site

• 120N, 0P, 0K, 0S

Acknowledgements

• NIAB CUF would like to thank Alex Godfrey and Will Gagg and their team at RJ

and AE Godfrey for all their help and support in conducting experiments and

trials during 2018

• AHDB staff involved in the SPot North programme including: Graham Bannister

and Amber Cottingham

• Branston staff for harvesting and assessing tuber quality, especially Oscar

Thacker and Nick Aldrich